Presently there are no known methods that combine the three key areas of synthesis, separation and screening. Other technologies which have partial accomplishments in these areas are based on solid phase parallel/combinatorial synthesis whereby synthesis, purification by washing and sometimes, but rarely, biological evaluation are performed (see for example “Combinatorial Chemistry: Synthesis and Application” eds. S. R. Wilson and A. W. Czarnik, John Wiley & Sons Inc., NY, 1997). These methods require attachment and sometimes cleavage reactions to and from a support. Furthermore, the reactions involved are restricted to those applicable for solid phase chemistry. The normal scope of synthetic chemistry maybe somewhat restricted here, since most reactions are developed in solution. Reactions are often driven to completion by the use of a vast excess of one of the reagents. Purification is usually achieved by sequentially washing the resin or solid support. Biological testing has been performed on compounds still attached to solid supports, though it is unknown as to how this effects the results of these assays, see e.g. WO 94/08051. Spot-synthesis involves the synthesis of compounds on a paper support (R. Frank, Tetrahedron (1992) 48, 9217-9232). Biological screening can then be performed upon the support. However, the purification of compounds is entirely reliant upon sufficient washing of the support. Furthermore, the technique is rather unidimensional in that reactions must be high yielding if not quantitative since the method lacks a separation step.
Solution chemistry has been used to try and overcome some of the disadvantages above. However, in order to screen compounds synthesised in solution, the compounds often need to be isolated. Furthermore, methods for purification can often be complex, requiring the use of sequestering reagents, extractions, column chromatography, etc. In both solution and in the solid phase it is critical that the chemistry is optimised. Chemistry validation is regarded as the bottle-neck in library synthesis and can be a substantial drain on resources. Today's technology is often very complex, time consuming and difficult to integrate. Expensive equipment is usually necessary to achieve the end-goal of screening new compounds.
Bioautography encompasses both the separation of compounds from a mixture and their subsequent biological testing, e.g. P. J. Houghton et al, Pharm. Pharmacol. Lett (1997), 7, 96-98. This technique, to our knowledge, has not been combined with synthesis. It has largely been used in the identification and isolation of natural products. The compounds are then screened in situ.
U.S. Pat. No. 6,029,498 describes a method for performing a chromatographic process under the influence of microwaves and a chromatographic column adapted therefor.
Bjørseth et al., Science, Vol 215, 1 January 1982, pp 87-89, describe a technique in which components in complex samples are separated on thin-layer chromatography plates and their mutagenic effect is registered directly on the plates by means of a Salmonella assay. Espinosa-Aguirre et al, Mutation Research 359 (1996) 133-140, describe the detection of bacterial mutagens by utilising the technique described by Bjørseth et al.
Thus it can be seen from the above discussion that it would be an improvement to the art to provide an integrated system for both combinatorial synthesis and bioassay or other such screening procedure.